1. Field of the Invention
The present invention relates generally to offshore platforms, and more specifically to an assembly for compensating for motion.
2. Background of the Invention
When servicing a subsea well from a floating vessel, tidal variations cause the vessel, as well as surface wellhead assemblies connected an upper end of a riser from the subsea well location, to drift. This phenomenon is commonly known as “tidal drift.” When servicing the well through the surface wellhead assembly, the servicing equipment is typically suspended above the surface wellhead assembly. The typical servicing equipment can be the equipment commonly known and associated in the art for coiled tubing, wireline, and snubbing well intervention work. The tidal drift can cause excessive forces to be experienced on the equipment that can damage or break the servicing equipment and the surface wellhead assembly.
Conventional devices used for accommodating for such movements are large and bulky in size. These devices are so large that they cannot be used within a drilling rig. Moreover, the conventional devices are not responsive to the tidal drift. Rather, the operator has to monitor the status of the equipment in response to tidal drift, and then manually adjust the device as needed. This process can be costly and dangerous, because it is desirous to keep the line supporting the servicing equipment taught so that as little weight as possible is supported by the surface wellhead assembly.